U.S. Pat. No. 5,192,292 (Cezana et al), assigned to the Assignee of the present invention, discloses a straight, or linear, rotatable arthroscopic tool and a powered rotary surgical handpiece for releasably chucking and rotatably driving such tool. The tool comprises a tubular outer member having a hollow base at its proximal end for releasably fixed chucking on the handpiece, an elongate, slim, tubular intermediate portion, or sleeve, fixedly extending forward from said base and having a distal tip portion terminating the distal end of the sleeve. The tool further comprises a rotatable inner member having a proximal end portion defining a hub for rotational driving by a rotor of the handpiece when the tool is chucked in the handpiece. The rotatable inner member further comprises an intermediate portion extending forward from and rotatable in fixed relation with the hub and ending in a distal tip portion. The hub protrudes rearwardly from the tubular outer member, whereas the intermediate portion and distal tip portion of the rotatable inner member are sleeved within the tubular outer member. The distal tip portion of the rotatable inner member lies within and is rotatable within the distal tip portion of the tubular outer member. The distal tip portions are provided with means for surgically working tissue of a patient at a surgical site on the patient. The tissue working means may for example, comprise coacting oval shearing slots, or windows, on the distal tip portions. In one unit according to the aforementioned patent, a toothed shearing edge on the inner member slot coacts in a shearing fashion with a cutting edge on the outer member slot.
In the tool disclosed in the aforementioned U.S. Pat. No. 5,192,292, the rotatable inner member is tubular and open from the distal tip portion thereof through the intermediate portion and to a location on the hub in communication through the handpiece with a suction source, for suctioning flowable material, including irrigation liquid and pieces of tissue, from the surgical site.
In this prior patented device, the hollow tubular inner member is snugly, though rotatably, supported within the tubular outer member such that the flow of suctioned flowable material from the surgical site to the handpiece is inside the hollow tubular inner member. Further, the inner and tubular outer member are substantially rigid so that both are necessarily straight, to allow rotation of the inner member within the outer member.
The present assignee, Stryker Corporation, under model designation 270-851, has for several years manufactured a tool generally similar to that described above but wherein the above-mentioned coacting shearing slots are absent. The rotatable inner member carries a burr at its distal end exposed through the open front and of the outer tubular member, and the inner rotatable member has a solid shaft of maximum diameter substantially less than the interior diameter of the outer tubular member so as to provide an annular clearance therebetween. The intermediate portion of the inner shaft is supported by several axially spaced bushings distributed along its length and supported by the interior wall of the outer tubular member. Such bushings are provided with axially extended grooves which are open radially and endwise to allow suction of flowable materials from the surgical site along the length of the tool to the handpiece radially between the shaft and the inner wall of the outer tubular member. Again, the outer tube and inner shaft are both rigid and are thus necessarily straight to allow relative rotation.
U.S. Pat. No. 5,152,744 (Krause et al), assigned to Smith and Nephew Dyonics, discloses a tool in which the rigid outer tubular member is curved near its distal end, so that the distal end is angled from the intermediate portion of the tool. The rotatable inner member is a hollow tubular member closely rotatably supported for rotation within the outer tubular member. The inner tubular member, adjacent its distal end, and in the curved portion of the outer tubular member, is purportedly made flexible enough to rotate within the curved outer tube in several alternative ways. In one embodiment, Krause reduces the diameter of the purportedly flexible portion and perforates it with closely axially and circumferentially spaced holes. Alternatively, Krause makes this portion purportedly flexible enough to rotate within the curved outer tube, by cutting therein axially and circumferentially close spaced, circumferentially extending, elongate chordal slots, the slots being connected by narrow circumferential and axial webs. The slots each extend almost halfway through the diameter of the inner tube. Axially adjacent pairs of these chordal slots are angularly shifted through 90.degree. with respect to each other. In a further embodiment, the purported flexibility sufficient to enable rotation of the inner tube within the curved portion of the outer tube is to be achieved axially close spaced, radially planar slots cut almost all the way through the thickness of the inner tubular member, leaving only a narrow web of axially extending tube material between the circumferential ends of each slot, and wherein axially alternate slots open in diametrically opposite directions, the slots each being filled and hence closed with a web of silicone rubber to prevent leakage of flowable material radially out of the flexible portion of the rotatable inner tube.
U.S. Pat. No. 4,646,738 (Trott), assigned to Concept, Inc., rather similarly discloses a curved tubular outer member snugly rotatably supporting therein a hollow tubular inner member. The latter has a purportedly flexible portion in the curved zone of the tubular outer member, and comprising a set of three spirally wound tubes of flat metallic ribbon which are disposed one within the other to provide inner, middle and outer spirally wound tubes. The inner, middle and outer spirals are wound in alternating opposite directions and are spot welded at each end to form a composite three-layer purportedly flexible tube. Torque applied to one end of such composite flexible tube is to be transmitted by alternate layers trying to expand (unwind) or trying to contract (wind up) such that the middle spiral is to either attempt to expand and be resisted by contraction of the outer layer or the middle spiral is to attempt to contract or wind up and be resisted by the inner spiral. Further, the three spirals are welded to each other by spot welds disposed longitudinally along the spirally wound composite tube.
Accordingly, the objects and purposes of the present invention include provision of a tool drivable by a powered rotative surgical handpiece, wherein the tool has a fixed outer tubular member with an angled portion near the distal end thereof and inner rotatable member with a flexible portion at the angled portion of the outer member, in which such tool overcomes apparent difficulties of the prior art, including avoiding excessive friction between angled, snugly radially telescoped inner and outer tubes during rotation of the inner tube, high torque and power expenditures, excessive heating, friction and heat induced fatigue or wear, cost and complexity and unreliability of manufacture of hollow flexible tube portions, possible migration of hard (e.g. bone) fragments into flexible inner rotor slots (which may impede closing thereof and hence flexing) and through such slots into a close clearance rotative interface between inner and outer members so as to upset rotating clearances therebetween, inability to withdraw the inner member rearwardly out of the outer member and replace same forwardly into the outer member, and the like.